OpenE2K
/
linux
6
0
Fork 0
Code Issues Pull Requests Releases Wiki Activity

ceph: fix potential race in ceph_check_caps 

[ Upstream commit dc3da0461c ]

Nothing ensures that session will still be valid by the time we
dereference the pointer. Take and put a reference.

In principle, we should always be able to get a reference here, but
throw a warning if that's ever not the case.

Signed-off-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
Jeff Layton 2020-03-20 16:45:45 -04:00 committed by Greg Kroah-Hartman
parent dac34dd4ef
commit 3e4ca8bf58
1 changed files with 13 additions and 1 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

14
fs/ceph/caps.c
View File

@ -2013,12 +2013,24 @@ ack:
if (mutex_trylock(&session->s_mutex) == 0) { if (mutex_trylock(&session->s_mutex) == 0) {
dout("inverting session/ino locks on %p\n", dout("inverting session/ino locks on %p\n",
session); session);
session = ceph_get_mds_session(session);
spin_unlock(&ci->i_ceph_lock); spin_unlock(&ci->i_ceph_lock);
if (took_snap_rwsem) { if (took_snap_rwsem) {
up_read(&mdsc->snap_rwsem); up_read(&mdsc->snap_rwsem);
took_snap_rwsem = 0; took_snap_rwsem = 0;
} }
mutex_lock(&session->s_mutex); if (session) {
mutex_lock(&session->s_mutex);
ceph_put_mds_session(session);
} else {
/*
* Because we take the reference while
* holding the i_ceph_lock, it should
* never be NULL. Throw a warning if it
* ever is.
*/
WARN_ON_ONCE(true);
}
goto retry; goto retry;
} }
} }